Evaluation of Techniques to Measure Chilling Injury in Tomato

Intact plants of four Lycopersicon species, Solanum lycopersicoides Dun. and a L. esculentum Mill. × S. lycopersicoides intergeneric hybrid at the four- to 11-leaf developmental stage were subjected to temperatures of 20° or 2.5°C for 72 hr. Plants were assayed for chilling injury by a visual rating of damage on specified leaflets (VRL), chlorophyll fluorescence (CF), electrolyte leakage (EL), and a visual rating of plants (VRP). Correlations of genotypic effects were significant between a) CF and VRL, b) CF and VRP, c) VRL and VRP, and d) VRP and EL. Correlations of the temperature × genotype interactions were highly significant between a) CF and VRL, b) CF and VRP, and c) VRL and VRP. CF was the most precise assay to quantify chilling injury. The means for CF for each of five leaflets from a single leaf produced similar separation of genotypes. Chilling resistance of an intergeneric hybrid between sensitive L. esculentum Mill. cv Sub-Arctic Maxi and resistant S. lycopersicoides suggested dominant, nuclear gene control.